Saturday, 4 May 2013

Russian Meteor Infrasound 'Heard' in U.S.

May 3, 2013 — How powerful was February's meteor that crashed into Russia? Strong enough that its explosive entry into our atmosphere was detected almost 6,000 miles away in Lilburn, Ga., by infrasound sensors -- a full 10 hours after the meteor's explosion. A Georgia Tech researcher has modified the signals and made them audible, allowing audiences to "hear" what the meteor's waves sounded like as they moved around the globe on February 15.

Infrasound signals associated with the Russian meteor impact on February 15, 2013, recorded nearly 9,600 km away in Lilburn, Georgia. The sound took about 10 hours to travel from Russia to Georgia. (Credit: The seismic data is distributed by the IRIS DMC, TA/USArray network/Image from video courtesy of Georgia Institute of Technology)

Lilburn is home to one of nearly 400 USArray seismic/infrasound stations in use in the eastern United States. They are part of a large-scale project named "Earthscope," an initiative funded by the National Science Foundation that studies Earth's interior beneath North America. The stations are mainly deployed to record seismic waves generated from earthquakes, but their sound sensors can record ultra long-period sound waves, also known as infrasound waves.

The human ear cannot hear these infrasound signals. However, by playing the data faster than true speed, Georgia Tech faculty member Zhigang Peng increased the sound waves' frequency to audible levels.